Effects of Nano-Iron Sulfide on Growth Performance, Antioxidant Status, Meat Quality, and Intestinal Microbiota in Broilers, and Tolerance Evaluation.

This study evaluated nano-iron sulfide (nFeS) as an iron source for bioavailability, biocompatibility, and tolerance in broilers. Broilers (Arbor Acres; males; initial body weight: 43.0 ± 0.4 g) were allocated between five diets: an iron-deficient basal diet (ID), or a basal diet with 80 mg Fe/kg as FeSO4; or 20, 40, or 80 mg Fe/kg as nFeS. The results showed that nFeS treatments (40, 80 mg/kg) improved average daily gain and feed conversion rates compared to ID and showed comparable or even superior effects relative to FeSO4 on growth performance within 1-21 days (p < 0.05). nFeS improved whole-blood hemoglobin (Hb) content and packed cell volume (PCV) percentages at day 21, while increasing serum SOD and GSH-Px activities at day 42. nFeS (40, 80 mg/kg) had or tended to deposit higher iron content in the liver, spleen, duodenum and serum than the FeSO4 groups. nFeS significantly increased breast meat lightness and redness compared with ID (p < 0.05) and showed comparable effects on postmortem pH, drip loss, and shear force relative to FeSO4. nFeS reshaped the microbial composition in the jejunum and cecum, particularly enriching the abundance of beneficial bacteria such as Lactobacillus in the jejunum. At a dose of up to 400 mg/kg, nFeS revealed no negative effects in broilers. In conclusion, nFeS is an effective iron supplement with high bioavailability and comparability, with additional benefits in shaping intestinal microbiota.